#include <iostream>

using namespace std;

const int N = 100010;

int m;
int stk[N], tt;

int main()
{
    cin >> m;
    while (m--)
    {
        string op;
        int x;

        cin >> op;
        if (op == "push")
        {
            cin >> x;
            stk[++tt] = x;
        }
        else if (op == "pop") tt--;
        else if (op == "print") for (int i = 1; i <= tt; i++) cout << stk[i]<<endl;
        else if (op == "setNull") tt = 0;
        else if (op == "empty") cout << (tt ? "NO" : "YES") << endl;
        else cout << stk[tt] << endl;
    }
    return 0;
}